SSS - Nukular Warhead - Chassis are Finished

[M Fowler]

rj,

From what I have gathered there seems to be some difference of opinion on this. One person said 12AX7 PI (standard Dumble, see the ODS schematics) and cathode follower driver direct coupled to the output tube grids.

Another talks about 12BH7 which is good as I picked up a Hammond Organ at local Habitat For Humanity loaded with tubes probably 24 would not be exaggerating it. 12AU7s, 12AX7s, 12BH7, 6V6s, 5U4, an a few more types I don't recall. I pulled some tubes and put into my latest Express and what a difference compared to current production tubes.

Another poster noted: According to what I've heard, the set-up in an SSS is similar...but uses a 12AX7 instead of a 12BH7 as a cathode-follower/driver. Plan on a bias supply of -150 volts...with a B+ of around 500. If you work the circuitry right, you can take the -150 off the bottom of a 650 volt PT (think MusicMan), leaving the remaining 500 for the B+. Cathode resistor on cathode-follower/driver S/B 100k if you want an exact clone.

Not sure what direction I am going

[M Fowler]

Further investigation shows this:

The SSS PI and post PI CF parts are as follows:

PI: 120k anode resistors

1M grid resistors
820 Ohm cathode, 24k tail resistor

Feedback Loop resistor 100 Ohm , 2k2 on Presence Pot to ground

Post PI CF:
150k CF grid resistors
100k (2W) cathode resistors

Think of the SVT 12BH7: coupling to Bias is with 330k , 30k

[Max]

Dumble & SSS builders,

Currently I plan to follow the SVT as I put together a prototype SSS schematic... unless someone has a convincing piece of info that the actual SSS was more Fender like.

Some pieces of info (if convincing or not-your own decision):

1. In this thread you see a picture of a SSS. Do you see something that looks like a SVT power amp?

2. SVT is 300 Watts. According to the known catalogues and SSS datasheets of Mr. Dumble there did never exist a 300 Watt SSS

3. According to the posts by Brandon and myself (We both do at least have some personal experience with Dumble SSS) there are at least three different variants of SSS PI/Driver setups:

a) only one 7025 as PI as in every ODS

b) two 7025. First PI, second Driver. "Phase Inverter" and "Driver" are the names Mr Dumble uses for these. They have not been made up by me.

c) One 12AU7 as "PI", one 12BH7 as "Driver" like in a 150W Dumbleland.

Perhaps it wood be a good idea if you

- first
decide what kind of SSS sound you liked best of those you have
heard live or recorded

-second
find out what special kind of SSS was played at these concerts or recording sessions.

-third
find out the technical details of this special SSS

-fourth
decide if you want to take all the trouble of cloning this special SSS you've liked best or better to buy one of the amps you find on the boutique market (Bludotone, Two Rock, Fuchs and maybe others) that are offered as being (more or less) SSS clones.

Trying one of these may perhaps spoil the fun you may see in investigating and then cloning the Dumble SSS. But perhaps you would be revarded with more time for Rock'N'Roll.

BTW: An original one that IMHO sounds really great (PI variant b)) is right now available at Overland Express.

Cheers and have fun

Max

[M Fowler]

Max all very good points and I thank you for your reply to rj's inquiry.

The SSS seems to be topically different as it evolves from HAD's mind and hands as years went by to meet the different players needs.

Mark

[thyx]

thanks, your kind critique is requested.

rj

Resistor going from PI coupling cap to bias pot S/B 330k...bias pot S/B 10k...resistor from pot to negative bias supply S/B 30k...control grid resistor to power tubes S/B 1.5k (not 47k)...cathode resistor S/B 100k, 2-watt...and tube S/B 12AX7.

The bias and plate-voltage supplies are set up a bit different, too.

[txbluesboy]

RJ, I have included a bypass position on my filters, which is my favorite position. I don't think I will use the filters much because I love the natural tone of this amp. The filters are just a brain exercise. They may prove useful to me at some point however. I still haven't come up with what I think is a good low filter. The high pass RC networks I have tried so far attenuate the volume to much for my liking as they filter the lows. Maybe this is just the nature of the beast? Terry

[RJ Guitars]

Max - thanks for taking some time to chat about the SSS...

1. In this thread you see a picture of a SSS. Do you see something that looks like a SVT power amp?

2. SVT is 300 Watts. According to the known catalogues and SSS datasheets of Mr. Dumble there did never exist a 300 Watt SSS

Well nothing that looks like a 300 watt Output section anyway... but the driver tube and the filtering section teases us a little to believe there was a little something borrowed from AMPEG in the SSS. Also there is some folklore that floats about that makes this connection. If you know for sure then I don't mind putting the notion to rest.

3. According to the posts by Brandon and myself (We both do at least have some personal experience with Dumble SSS) there are at least three different variants of SSS PI/Driver setups:

a) only one 7025 as PI as in every ODS

b) two 7025. First PI, second Driver. "Phase Inverter" and "Driver" are the names Mr Dumble uses for these. They have not been made up by me.

c) One 12AU7 as "PI", one 12BH7 as "Driver" like in a 150W Dumbleland.

This is a great contribution to us. Might explain some of the origin of the folklore and adds to the public knowledge base on these amps. Thank you for this, it is good stuff!

Perhaps it wood be a good idea if you

- first
decide what kind of SSS sound you liked best of those you have
heard live or recorded

-second
find out what special kind of SSS was played at these concerts or recording sessions.

-third
find out the technical details of this special SSS

I can see this could be useful if for the musician who has identified something very specific they want to hear from their amp, but that is not the case for me. I am an experimenter, builder, student, and teacher and knowing that these amps are famous for great clean tone and singing sustain makes the circuit interesting to me even if had never heard a sound clip from one of them. Sounding like SRV would be cool, but it's not a goal for me.

-fourth
decide if you want to take all the trouble of cloning this special SSS you've liked best or better to buy one of the amps you find on the boutique market (Bludotone, Two Rock, Fuchs and maybe others) that are offered as being (more or less) SSS clones.

Trying one of these may perhaps spoil the fun you may see in investigating and then cloning the Dumble SSS. But perhaps you would be revarded with more time for Rock'N'Roll.

You sorted that one out for yourself... buying an amp can't satisfy the amp builder habit much less the experimenter intellect.... maybe not a surprise response given that this is an amp builders forum. For me, even cloning an amp is not rewarding in the way that experimenting and sorting out what possessed the original builder to make things the way they did.

BTW: An original one that IMHO sounds really great (PI variant b)) is right now available at Overland Express.

I like this note... variant b sorta fits into some of my preconceived notions about what I thought I might build. I've seen a couple amps and even built one of my own using a driver tube and I liked the results. In this case I am really trying to grasp the concept of how that the driver tube is key to reducing distortion. That would be a useful piece of technology for other amp projects as well.

If you don't mind a little follow up discussion on the output section, I am curious if you believe that it is basically the same as the ODS? I see the Fender iron and it seems that the extra power supply stuff isn't obvious in the one SSS gut shot we've got. Four 6L6's or maybe 6550's and the iron is the same as an ODS? Curious if you can elaborate?

Thanks,

rj

[markr14850]

People interested in the benefits of a driver towards reducing blocking distortion might find an interesting read here: http://www.tubelab.com/powerdrive.htm

[Structo]

Wow I just spent quite a while on that website.

Pretty amazing read.

Thanks!

[RJ Guitars]

As I start to figure out what the AMPEG circuit does (recognizing that it may or may not be relevant), and considering what Max has offered, I have started to gravitate toward an idea of what I think the phase inverter and output section could look like for my own SSS.

I have a Dumble 300SL schematic that I picked up somewhere that is very similar to the AMPEG SVT circuit, although maybe a bit simpler. What I have found in looking at the AMPEG circuit is that I believe that extra set of transformer windings is all about separating the B+ voltage to the phase inverter, driver circuit, and power tube screens from the voltage swings on the primary windings of the main transformer. This is possibly more important in a Bass amp than a guitar amp but would no doubt help in the efforts to keep things clean. I'll add my own drawing of the AMPEG circuit for the curious and give you the chance to check and challenge my logic.

The 300SL schematic I have does not use the separate transformer and takes the PI and driver B+ from same secondary as all the other B+ nodes. This adds to my thoughts that the separate transformer might not be necessary for a guitar amp.

Based upon Max's mention of two different iterations of SSS amps using a driver after the phase inverter, I'm inclined to go with either his option b or c, using the cathode output as the driver into the power tubes. I don't plan to use a separate transformer or attempt any isolation of the B+ nodes from each other beyond the standard resistors and filter caps.

I'll try to put that into a schematic and get it posted.

rj

[Max]

If you don't mind a little follow up discussion on the output section, I am curious if you believe that it is basically the same as the ODS?

Variant a) was Brandon's find. I've only met b) and c). b) and c) are of course not like 50/100W ODS.

Henry's could perhaps be a) from what I see on the pictures (caution I'm no tech!).

But as never seen a) in real live:
Sorry, but I don't know if the output section of Henry's amp is similar to the one of an ODS from the same period or not.

Have fun

Max

[RJ Guitars]

Hey guys,

Here is some info to contemplate... If you consider building an SSS using the Twin style AB763 power amp and the AB763 Reverb, then you've essentially got a Twin Reverb with an ODS preamp mod. Not bad criteria for a good sounding amp and from what we can gather, a good first approximation for an SSS build. It also begs the question, "How different is this from an ODS minus the OD and add Reverb"? A second lingering question also remains, what is the key to the "singing" associated with this amp?

The SSS seems to have at least three unique builds if I read Max's notes correctly. Using the Twin power amp makes it the simplest of the lot although I have also included a look at one with a cathode driver. I haven't bothered to draw up the AMPEG power amp because... well it's a lot of work and Max has convinced me that it's not likely used in any SSS amps... everybody feel free to send me any proof otherwise and I'll draw it up.

The HiFi guys tell me that the cathode driver will not likely be cleaner until the amp is pegged (they don't expect this to have much dirt anyway). However, they did mention that it might have a little flavor all it's own... for better or worse, you'll just have to try it.

I'm under no illusion that this is exactly how HAD did it and if you work from these schematics the "Unverified Draft" watermark in the drawing may prove to be significant.

Kind comments are welcome,

rj

[txbluesboy]

Great work RJ

[RJ Guitars]

I came up with a low filter that works well. I also tweeked the values on the high filter to allow the use of a lower resistance series resistor, thinking this might be less of a tone drain.

Thanks Terry,

Any commentary to go along with your filter designs? I'm curious if you find them to be something that you could never accomplish using the amp and guitar tone controls?

Well, this gives us every component of the schematic in some form or another. I'm working on my draft layout for the boards... maybe later this week.

rj

[RJ Guitars]

I updated my iteration of the SSS preamp...

I cleaned up the component numbering a bit and found one wiring error... a significant one. If you've got the old schematic, maybe better toss it and replace it with this one.

I'll work on the preamp board layout next... looking forward to actually building the amp.

rj